Finger biometric sensor including laterally adjacent piezoelectric transducer layer and associated methods

ABSTRACT

A finger biometric sensor may include a finger biometric sensing layer having an upper major surface and at least one sidewall surface adjacent thereto. The finger biometric layer may be for generating signals related to at least one biometric characteristic of the user&#39;s finger when positioned adjacent the first major surface. The finger biometric sensor may also include a piezoelectric transducer layer coupled to the at least one sidewall surface of the finger biometric sensing layer and a plurality of electrically conductive layers coupled to the piezoelectric transducer layer to define transducer electrodes. At least one of the electrically conductive layers may also cooperate with the finger biometric sensing layer for sensing the at least one biometric characteristic.

RELATED APPLICATION

This application is a continuation of pending Ser. No. 12/537,711 filedAug. 7, 2009, the entire disclosure of which is hereby incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of electronics, and, moreparticularly, to the field of finger biometric sensors, and associatedmanufacturing methods.

BACKGROUND OF THE INVENTION

Fingerprint sensing and matching is a reliable and widely used techniquefor personal identification or verification. In particular, a commonapproach to fingerprint identification involves scanning a samplefingerprint or an image thereof and storing the image and/or uniquecharacteristics of the fingerprint image. The characteristics of asample fingerprint may be compared to information for referencefingerprints already in a database to determine proper identification ofa person, such as for verification purposes.

A particularly advantageous approach to fingerprint sensing is disclosedin U.S. Pat. No. 5,953,441 to Setlak and assigned to the assignee of thepresent invention. The fingerprint sensor is an integrated circuitsensor that drives the user's finger with an electric field signal andsenses the electric field with an array of electric field sensing pixelson the integrated circuit substrate.

U.S. Pat. No. 6,289,114 to Mainguet discloses a fingerprint sensor thatincludes a finger sensing integrated circuit (IC). The finger sensing ICincludes a layer of piezoelectric or pyroelectric material placedbetween upper and lower electrodes to provide electric signalsrepresentative of an image of the ridges and valleys of the fingerprint.

A particularly advantageous approach to multi-biometric fingerprintsensing is disclosed in U.S. Pat. No. 7,361,919 to Setlak, which isassigned to the assignee of the present invention and is incorporated inits entirety by reference. The Setlak patent discloses a multi-biometricfinger sensor sensing different biometric characteristics of a user'sfinger that have different matching selectivities.

It may also be desirable to have a finger biometric sensor powered downor in a low power consumption mode until a finger is placed in aposition to be sensed. The finger biometric sensor may desirably detectwhen the finger is in a sensing position and then activate itself andany other devices, such as processors, needed to perform the functionsdesired by the user.

Several approaches for detecting the presence of a finger in a desiredposition are known. Typically, in some approaches, a small part of afinger imaging system may be activated on a periodic basis to determineif a finger is present. A negative aspect of these approaches is thatthey dissipate power in the finger biometric sensor, and/or itssupporting circuitry, during a time when the finger imaging system iswaiting for the finger to appear. Quiescent power consumption while in afinger detect (waiting) mode drains a battery in a portable electronicdevice.

In an attempt to reduce the quiescent power consumption, some fingerpresence detection approaches have been proposed where the fingerprintsensor is mounted on a mechanically actuated electrical switchingelement. Finger pressure on the fingerprint sensor moves the switchingelement, causing the switch to close and activating sensor electronicsor the supporting circuitry. While this approach may consume noquiescent current, it may be difficult to reliably implement because itrequires the finger biometric sensor itself to be a moving part.

Several approaches to finger biometric sensors including a switch aredisclosed in U.S. Pat. No. 4,120,585 to DePalma et al.; U.S. Pat. No.6,522,773 to Houdeau; U.S. Pat. No. 6,912,299 to Hoshino et al.; andU.S. Pat. No. 7,266,226 to Hwang. U.S. Published Application No.2004/0155752 to Radke also discloses a switch associated with a fingerbiometric sensor. U.S. Patent Application No. 2007/0076923 to Chiu, forexample, discloses a finger sensing device that has a power controlswitch at the tip of the sensor panel, and a second switch underneaththe finger sensor to initiate the finger sensing operation.

Other finger biometric sensors may include power controls integratedwithin the finger print imaging system, or adjacent the fingerprintsensor, such as disclosed in U.S. Published Application No. 2006/0239517to Creasy et al. Still, other finger biometric sensors, such asdisclosed in U.S. Pat. No. 5,940,526 to Setlak et al., include powercontrol to only active portions of the finger sensor, thus resulting ina standby mode.

Still further, it may be desirable to provide the user with tactilefeedback when a finger is placed on the biometric finger sensor. U.S.Published Application No. 2001/0017934 to Paloniemi et al. discloses afingerprint sensor mounted on a switch. When the fingerprint sensor istapped, the switch is operated and provides an audible and/or tactilefeedback to a user, for example, by movement of a domed membrane. U.S.Published Application No. 2005/0111707 to Bohn et al. discloses afingerprint scanner that provides a tactile and/or audible indicationfrom an end of scan switch located on a housing frame.

U.S. Published Application No. 2006/0239517 to Creasey et al., asbriefly described above, further discloses a finger sensor mounted on ahousing of a device and providing feedback to a user in the form ofphysical feeling. A platen receives a user's finger and is coupled to abase of the housing. An activation sensor, which may be a piezoelectricsensor, is coupled to the platen and detects force on the platen inresponse to a user's finger pressed on the sensor.

SUMMARY OF THE INVENTION

In view of the foregoing background, it is therefore an object of thepresent invention to provide a finger biometric sensor with powercontrol and/or feedback features.

This and other objects, features, and advantages in accordance with thepresent invention are provided by a finger biometric sensor that mayinclude a finger biometric sensing layer having opposing first andsecond major surfaces and for generating signals related to at least onebiometric characteristic of the user's finger when positioned adjacentthe first major surface. A piezoelectric transducer layer may be coupledto the second major surface of the finger biometric sensing layer. Aplurality of electrically conductive layers may also be coupled to thepiezoelectric transducer layer to define transducer electrodes.Accordingly, a finger biometric sensor is provided that may includepower control and/or feedback features.

More particularly, the finger biometric sensor may further include adrive circuit coupled to the transducer electrodes to drive thepiezoelectric transducer layer to impart a force to the user's finger,for example. The finger biometric sensor may further include a sensecircuit coupled to the transducer electrodes to sense from thepiezoelectric transducer layer a force imparted by the user's finger.Advantageously, the finger biometric sensor may provide tactile feedbackto the user's finger, it may provide finger presence detection for powercontrol, or it may provide both.

Additionally, the finger biometric sensor may further include a readingcircuit coupled to the finger biometric sensing layer for readingsignals therefrom, for example. The finger biometric sensor may alsoinclude a power up circuit for selectively powering up the readingcircuit based upon the sense circuit. The sense circuit may generate apressure output signal related to an amount of pressure applied by theuser's finger, for example, for other functions besides power control.

The finger biometric sensor may further include a matcher coupled to thefinger biometric sensing layer for determining a match based upon the atleast one biometric characteristic of the user's finger. The fingerbiometric sensor may also include a navigation circuit coupled to thetransducer electrodes for performing at least one navigation function,for example. Additionally, the finger biometric sensor may also includea feedback circuit coupled to the transducer electrodes for performingat least one feedback function. The feedback circuit and/or thenavigation circuit may be embodied in a processor, which may be includedwithin or external to the finger biometric sensor or shared between thesensor and external circuitry.

The finger biometric sensing layer may include or be part of anintegrated circuit. Additionally, the finger biometric sensor mayinclude a mounting substrate below the piezoelectric transducer layer.

Another aspect is directed to a method for making a finger biometricsensor. The method may include providing a finger biometric sensinglayer having opposing first and second major surfaces and for generatingsignals related to at least one biometric characteristic of the user'sfinger when positioned adjacent the first major surface. The method mayfurther include coupling a piezoelectric transducer layer to the secondmajor surface of the finger biometric sensing layer. The method maystill further include coupling a plurality of electrically conductivelayers to the piezoelectric transducer layer to define transducerelectrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a cellular telephone including afinger biometric sensor in accordance with the present invention.

FIG. 2 is a schematic cross-sectional view of the finger biometricsensor shown in FIG. 1.

FIG. 3 is a schematic block diagram of the finger biometric sensor andrelated circuitry shown in FIG. 1.

FIG. 4 is a more detailed schematic block diagram of the fingerbiometric sensor and related circuitry shown in FIG. 3.

FIG. 5 is a schematic block diagram of another embodiment of a fingerbiometric sensor and related circuitry in accordance with the presentinvention.

FIG. 6 is a more detailed schematic block diagram of the fingerbiometric sensor and related circuitry of FIG. 5.

FIG. 7 is a schematic block diagram of yet another embodiment of afinger biometric sensor and related circuitry in accordance with thepresent invention.

FIG. 8 is a more detailed schematic block diagram of the fingerbiometric sensor and related circuitry of FIG. 7.

FIG. 9 is a schematic block diagram of another embodiment of the fingerbiometric sensor and related circuitry in accordance with the presentinvention.

FIG. 10 is a schematic cross-sectional view of another embodiment of thefinger biometric sensor.

FIG. 11 is a perspective view of another embodiment of the fingerbiometric sensor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout, and prime and multiple primenotations are used to indicate similar elements in differentembodiments.

Referring initially to FIGS. 1-4, an embodiment of a finger sensor 10 inaccordance with the present invention are now described. The fingersensor 10 is illustratively mounted on an exposed surface of a cellulartelephone 50. Of course, the finger sensor 10 can also be used otherportable and stationary electronic devices as well.

The cellular phone 50 includes a housing 51, a display 52 carried by thehousing, and processor/operating circuitry 53 also carried by thehousing and connected to the display and to the finger sensor 10. Anarray of input keys 54 are also provided and used for conventionalcellphone dialing and other applications as will be appreciated by thoseskilled in the art.

The finger sensor 10 may be of the slide type where the user's finger 21slides over the sensing area to generate a sequence of finger images.Alternatively, the finger sensor 10 could be of the static placementtype, where the user simply places his finger 21 onto the sensingsurface to generate a finger image. Of course, the finger sensor 10 mayalso include circuitry embedded therein and/or in cooperation with theprocessor/circuitry 53 to provide menu navigation and selectionfunctions, tactile feedback, and/or power up functions as will beappreciated by those skilled in the art and as described in furtherdetail below.

Referring more particularly to FIG. 2, the finger biometric sensor 10includes a finger biometric sensing layer 11 having opposing first andsecond major surfaces 12, 13 and for generating signals related to atleast one biometric characteristic of the user's finger when positionedadjacent the first major surface. The finger biometric sensor 10 mayinclude electric field sensing pixels, for example, as described in U.S.Pat. No. 7,358,515, and assigned to the assignee of the presentapplication, the entire contents of which are herein incorporated byreference. Other finger biometric sensing technologies may be used, aswill be appreciated by those skilled in the art.

A piezoelectric transducer layer 14 is illustratively coupled to thesecond major surface 13 of the finger biometric sensing layer 11. Thepiezoelectric transducer layer 14 may be a polyvinylidene fluoridematerial, or more specifically Kynar®, which is available from Arkuna,Inc., of Philadelphia, Pa. A polyvinylidene fluoride material canadvantageously be fabricated down to a thickness to about 25 microns,for example, thus reducing the overall size impact to the fingerbiometric sensor 10. Other piezoelectric materials may be used, such aspiezo-ceramic materials or piezo-plastic materials, for example.

Moreover, the piezoelectric transducer layer 14 may be applied to thefinger biometric sensor 10 as a pre-formed film, for example.Alternatively, the piezoelectric transducer layer 14 can be printed orspun. However, if the piezoelectric transducer layer 14 is notpre-formed, it may be polarized as part of its manufacturing process.Polarization of the piezoelectric transducer layer 14 typically involvesusing controlled high-voltage corona discharges across the piezoelectrictransducer layer. The piezoelectric transducer layer 14 may be appliedusing other methods, or in other forms, as will be appreciated by thoseskilled in the art.

Electrically conductive layers 16, 17 are coupled to the piezoelectrictransducer layer 14 to define transducer electrodes. More particularly,the upper conductive layer 16 may be considered as a voltage referenceplane and is illustratively coupled between the finger sensing layer 11and the piezoelectric transducer layer 14. Additionally, the lowerconductive layer 17 may be considered as a voltage collection layercoupled to a bottom of the piezoelectric transducer layer 14. As will beappreciated by those skilled in the art, a piezoelectric voltage isgenerated between the upper conductive layer 16 and the lower conductivelayer 17 when a force is imparted by a user's finger to thepiezoelectric transducer layer 14 via the intervening electricallyconductive layer 16. In other embodiments there may be no interveninglayer or more than one intervening layer.

The finger biometric sensing layer 11 is advantageously packaged as anintegrated circuit, for example, in a ball grid array packageillustratively including the mounting substrate 27 below theelectrically conductive layer 17, and the array of electricallyconductive balls 37 carried by the substrate. Other packagingarrangements will be appreciated by those skilled in the art.

A finger drive electrode 18 is illustratively positioned on the mountingsubstrate 27 and is separated from the biometric sensing layer 11 andthe piezoelectric transducer layer 14 by a molded plastic ring 19. Thisfinger drive electrode 18 is advantageously used with electric fieldsensing pixels as will be appreciated by those skilled in the art, butmay not be needed for other sensing technologies.

Referring more particularly to FIGS. 3-4, the finger biometric sensor 10includes a drive circuit 22 that is illustratively coupled to thetransducer electrodes, that is, the electrically conductive layers 16,17 to impart a force to the user's finger 21. More particularly, thedrive circuit 22 advantageously generates a drive voltage waveform thatis applied to the piezoelectric transducer layer 14, which, in turn,generates a mechanical force on a user's finger 21 when positionedadjacent the first major surface of the finger biometric sensing layer11. One possible implementation of a drive circuit 22 includes a zenerdiode 35 coupled in parallel with the electrically conductive layers 16,17 to operate as a shunt regulator, and a drive amplifier 36 coupled tothe zener diode, as illustrated in FIG. 4. As will be appreciated bythose skilled in the art, the piezoelectric transducer layer 14 willvibrate when the drive circuit 22 provides an AC voltage to thepiezoelectric transducer layer. The drive circuit 22 may drive thepiezoelectric transducer layer 14 at voltage levels similar to an audioamplifier driving a piezoelectric headphone, for example.

The vibration of the piezoelectric transducer layer 14 advantageouslyprovides tactile or haptic feedback to the user. Additionally, properenvelope shaping of the waveform along with fine-tuning of the frequencyof short AC signal bursts from the drive circuit 22 to the piezoelectrictransducer layer 14 can give the user the tactile impression of a click.This feedback may be particularly helpful to a user performing anavigation function on an electronic device, such as the cellphone 50,for example, where a user is scrolling down a menu and the sensorgenerates a click each time the cursor crosses from one menu item to thenext. Other types of tactile feedback different than a click, such as alonger duration vibration, may be used, and may be used for otherapplications than menu scrolling, as will be appreciated by thoseskilled in the art.

Referring now additionally to FIGS. 5-8, the finger biometric sensor 10′includes a sense circuit 23′ that is coupled to the electricallyconductive layers 16′, 17′ to sense a voltage generated by thepiezoelectric transducer layer 14′ based upon a force imparted by theuser's finger 21′. The sense circuit 23′ may be used as a standalonecircuit or in conjunction with other circuitry.

When a user's finger 21′ imparts a force on the piezoelectric transducerlayer 14′ via the intervening electrically conductive layer 16′, anelectrical charge displacement signal or voltage signal is generatedbetween the electrically conductive layers 16′, 17′. The voltage signalwill vary depending on the amount of force received by the piezoelectrictransducer layer 14′.

One possible implementation of a sense circuit 23′ includes a zenerdiode 35′ coupled in parallel with the electrically conductive layers16′, 17′ to operate a shunt regulator with outputs that may be coupledto a level sensitive wake-up input or analog measurement input, forexample, as shown in FIG. 6. This implementation may be particularlyadvantageous for power control applications.

The sense circuit 23′ may also generate a pressure output signal relatedto an amount of pressure applied by the user's finger 21′. The amount ofapplied pressure can advantageously be used to enhance a user interfaceor enhance menu navigation, for example. For example, the pressureinformation may be advantageously used as a second measurement dimensionto assist both fingerprint verification and cursor or controlnavigation. In a cursor or control navigation mode, a measured increasein pressure, as indicated by an increase in the voltage of the signal,could be interpreted as a command from the user to accelerate thedirected cursor movement. Alternatively, a relaxation of pressure, asindicated by a reduction in voltage of the signal, can be interpreted asa command to slow down the cursor movement. It should be understood thatother conventions for navigation or control may be used based upon thepressure applied by the user's finger 21′.

When used in analog finger pressure measurements, the piezoelectrictransducer layer 14′ may be coupled to an analog input port, or thesignal may be conditioned using adjustable attenuators, or adjustablegain amplifiers. Where readout of the finger pressure is desired, acharge amplifier, or an electrical integrating circuit, includingappropriate reset circuitry, may be used to convert the chargedisplacement generated by the piezoelectric transducer layer 14′ into avoltage proportional to the actual pressure. This circuitry may beincluded on the finger biometric sensor 10′ or a boot device external tothe finger biometric sensor. Other arrangements may be implemented, aswill be appreciated by those skilled in the art.

Referring now to FIG. 7, in addition to the sense circuit 23″ asdescribed above, in other embodiments, the finger biometric sensor 10″also illustratively includes a reading circuit 24″ coupled to the fingerbiometric sensing layer 11″ for reading signals therefrom. A power upcircuit 25″ selectively powers up the reading circuit 24″ based upon thesense circuit 23″. More particularly, the sense circuit 23″ senses thesignal or the presence of the force on the piezoelectric transducerlayer 14″ via the intervening electrically conductive layer 16″ andcooperates with the power up circuit 25″ to selectively power up thereading circuit 24″ based upon the signal or force.

The reading circuit 24″ reads signals from the finger biometric layer11″. The signals may be fingerprint image signals, or signalsrepresenting other finger biometrics. Advantageously, by selectivelypowering up the reading circuit 24″ based upon the charge displacementor pressure signal from an applied force, the finger biometric sensor10″ provides a zero power consumption finger detection capability whilein a standby mode, or finger-waiting mode. Thus, overall system powerconsumption is reduced and battery life in the portable device isincreased.

The finger biometric sensor 10″ also illustratively includes a matcher26″ coupled to the finger biometric sensing layer 11″ for determining amatch based upon the at least one biometric characteristic of the user'sfinger 21″. The matcher 26″ may include or cooperate with a memory 27″to store biometric characteristics. Each circuit described above may beused alone or in combination with the other circuits described herein orother circuitry that may be included in the finger biometric sensor 10″or part of a host device, or be included in both the finger biometricsensor or the host device, for example.

Moreover, the power up circuit 25″ can also be used to wake up thefinger biometric sensor 10″ when a finger 21″ is first applied byconnecting the pressure signal to an interrupt line or other wake-up pinin the system. The interrupt line or other wake-up pin may be, forexample, on or off the finger biometric sensor 10″. In other words, thewake-up pin may be part of a host processor in a host device.

Referring now additionally to FIG. 8, a possible implementation of thesense circuit 23″ and the power up circuit 25″ includes a zener diode35″ that is coupled in parallel with the electrically conductive layers16″, 17″ to operate as a shunt regulator with out puts that may becoupled to an asynchronous latch 38″. The asynchronous latch 38″ isillustrated as an SR type, but other types may be used. The outputs ofthe asynchronous latch 38″ may feed the power up circuit 25″, whichillustratively includes a power switching device 39″. The powerswitching device 39″ and the asynchronous latch 38″ may be part of thefinger biometric sensor 10″ or part of a host processor or hostintegrated circuit, or part of both, for example. Using the voltagelimiting components advantageously reduces the amount of quiescent powerconsumption, as will be appreciated by those skilled in the art. Othercomponents and configurations, such as a Schmidt trigger or a voltagereduction network, may be used.

Referring now additionally to FIG. 9, a processor 28′″, which includes anavigation module or circuit 29′″ and a feedback module or circuit 33′″,is illustratively included in the finger biometric sensor 10′″ and maybe coupled to the electrically conductive layers 16′″, 17′″. While theprocessor 28′″ is illustratively included in the finger biometric sensor10′″, it may be external to the finger biometric sensor, for example, ona host device, or may be included on both the finger biometric sensor orhost device. Still further, while the processor 28′″ illustrativelyincludes both the navigation circuit 29′″, to perform the navigationfunctions as discussed above, and the feedback circuit 33′″, to provideuser feedback as discussed above, either circuit may be usedindependently of the other. Moreover, other modules or circuits may beincluded in the processor 28′″ to perform other functions or cooperatewith other circuits to perform those functions.

In an alternate embodiment, as illustrated in FIG. 10, a fingerbiometric sensor 40 includes a finger biometric sensing layer 41 havingan upper major surface 42 and sidewall surfaces 43 a-43 b adjacentthereto. The biometric sensing layer 41 is for generating signalsrelated to at least one biometric characteristic of the user's fingerwhen positioned adjacent the upper major surface. A piezoelectrictransducer layer 45 is adjacent the sidewall surfaces 43 a-43 b of thefinger biometric sensing layer 41. The piezoelectric transducer layer 45is similar in material and form to the piezoelectric transducer layer 14described above.

Ring-shaped, upper and lower, electrically conductive layers 46, 47 arecoupled to the piezoelectric transducer layer 45 to define transducerelectrodes. More particularly the upper conductive layer 46 may alsoserve as a finger drive electrode and is coupled between the fingersensing layer 41 and the piezoelectric transducer layer 45. The upperconductive layer 46 advantageously has a shared function as both a driveelectrode for the finger sensing layer 41 and one of the transducerelectrodes for the piezoelectric transducer layer 45. A shared functionelectrode advantageously reduces the number of electrodes, and thus mayreduce the overall package size of the finger biometric sensor 40.However, in some embodiments, the electrode(s) may not be shared, andadditional electrode(s) may be included.

A second transducer electrode provided by the lower conductive layer 47may be considered as the piezoelectric voltage electrode and isillustratively coupled to the bottom of the piezoelectric transducerlayer 45. As will be appreciated by those skilled in the art, apiezoelectric voltage is generated between the conductive layers 46, 47when a force is imparted by a user's finger to the piezoelectrictransducer layer 45 via the intervening electrically conductive layer46. In other embodiments there may be no intervening layer or more thanone intervening layer.

The finger biometric sensing layer 41 is advantageously packaged as anintegrated circuit, for example. Other packaging arrangements will beappreciated by those skilled in the art. Additionally, a flexiblemounting substrate 51 overlays the piezoelectric transducer layer 45 andthe finger biometric sensing layer 41, and is a Kapton® material,available from E. I. du Pont de Nemours and Company. Other substratematerials may be used. An underfill 52 provides separation between theflexible mounting substrate 51 and the finger biometric sensing layer41. Additionally the piezoelectric transducer layer 45 and the fingerbiometric sensing layer 41 are joined by an adhesive 53. The adhesive 53may also be used to join other components and layers, as will beappreciated by those skilled in the art. An optional sealing ring 54 isprovided overlapping a portion of the flexible mounting substrate 51.

Similar to the finger biometric sensor 10 embodiments described above inFIGS. 1-3, the finger biometric sensor 40 may be included in a cellulartelephone 50, or other portable electronics device, and also may includea drive circuit 22. The drive circuit 22 is coupled to the transducerelectrodes, or more particularly, to the upper conductive layer 46 andthe lower conductive layer 47 to drive the piezoelectric transducerlayer 45 to impart a force to the user's finger. Additionally, thefinger biometric sensor 40 may include a sense circuit 23 coupled to theupper conductive layer 46 and the lower conductive layer 47 to sensefrom the piezoelectric transducer layer 45 a force imparted by theuser's finger.

Still further, the finger biometric sensor 40 may include a readingcircuit 24 coupled to the finger biometric sensing layer 41 for readingsignals therefrom. A power up circuit 25 may also be included forselectively powering up the reading circuit based upon the sense circuit23. The sense circuit 23 may generate a pressure output signal relatedto the amount of pressure applied by the user's finger. The fingerbiometric sensor 40 may include a matcher 26 coupled to the fingerbiometric sensing layer 41 for determining a match based upon the atleast one biometric characteristic of the user's finger, as is similarin structure and implementation to the matcher 26 described above. Thesecircuits 22, 23, 24, 25, 26 as they are coupled to the finger biometricsensor 40, are similar in structure and function to the circuitsdescribed above for the finger biometric sensor embodiments illustratedin FIGS. 1-8.

Similarly, a processor 28, which includes a navigation circuit 29 and afeedback circuit 33, is included in the finger biometric sensor 40 andmay be coupled to the upper conductive layer 46 and the lower conductivelayer 47. While the processor 28 may be included in the finger biometricsensor 40, it may be external to the finger biometric sensor, forexample, a host processor. Still further, while the processor 28illustratively includes both the navigation circuit 29 and the feedbackcircuit 33, either circuit may be used independently of the other.

Referring now to FIG. 11, the finger biometric sensor 70 illustrativelyincludes a flex tape or a tab interconnect 73 cooperating with thebiometric sensing layer 72. The biometric sensing layer 72 includes asensing surface 71 and a sensor back cover 78 enclosing the biometricsensing layer. The upper conductive layer 76 is illustratively coupledto the bottom of the sensor back cover 78 of the biometric sensing layer72. The piezoelectric transducer layer 74 is illustratively coupled tothe upper conductive layer 76. The lower conductive layer 77 is coupledto the bottom of the piezoelectric transducer layer 74. The flex tape,or tab interconnect 73, advantageously attaches to a circuit (not shown)so that the sensing surface 71 is exposed through an opening in a hostdevice housing for surface access by the user's finger, for example.

Returning again to FIGS. 1-3, another aspect is directed to a method ofmaking a finger sensor 10. The method includes providing a fingerbiometric sensing layer 11 having opposing first and second majorsurfaces 12, 13. The finger biometric sensing layer 11 is for generatingsignals related to at least one biometric characteristic of the user'sfinger 21 when positioned adjacent the first major surface 12. Themethod further includes coupling a piezoelectric transducer layer 14 tothe second major surface 13 of the finger biometric sensing layer 11.The method further includes coupling two electrically conductive layers,the upper conductive layer 16, and the lower conductive layer 17, to thepiezoelectric transducer layer 14 to define transducer electrodes.

Returning again to FIG. 10, another aspect is directed to another methodof making the finger sensor 40. The method includes providing a fingerbiometric sensing layer 41 having an upper major surface 42 and sidewallsurfaces 43 a-43 b adjacent thereto. The finger biometric sensing layer41 is for generating signals related to the user's finger whenpositioned adjacent the upper major surface 42. The method furtherincludes coupling a piezoelectric transducer layer 45 to the sidewallsurfaces 43 a-43 b of the finger biometric finger sensing layer 41. Themethod further includes coupling electrically conductive layers, or moreparticularly, the upper conductive layer 46 and the lower conductivelayer 47, to the piezoelectric transducer layer 45 to define transducerelectrodes.

Many modifications and other embodiments of the invention will come tothe mind of one skilled in the art having the benefit of the teachingspresented in the foregoing descriptions and the associated drawings.Therefore, it is understood that the invention is not to be limited tothe specific embodiments disclosed, and that modifications andembodiments are intended to be included within the scope of the appendedclaims.

That which is claimed is:
 1. A finger biometric sensor comprising: afinger biometric sensing layer having opposing first and second majorsurfaces and for generating signals related to at least one biometriccharacteristic of a user's finger when positioned adjacent the firstmajor surface; a piezoelectric transducer layer adjacent the secondmajor surface of said finger biometric sensing layer; a plurality ofelectrically conductive layers coupled to said piezoelectric transducerlayer to define transducer electrodes; and a finger drive electrodeadjacent said finger biometric sensing layer and said piezoelectrictransducer layer, and configured to couple a radio frequency (RF) signalwith the user's finger.
 2. The finger biometric sensor according toclaim 1 further comprising a drive circuit coupled to said transducerelectrodes to drive said piezoelectric transducer layer to impart aforce to the user's finger.
 3. The finger biometric sensor according toclaim 1 further comprising a sense circuit coupled to said transducerelectrodes to sense from said piezoelectric transducer layer a forceimparted by the user's finger.
 4. The finger biometric sensor accordingto claim 3 further comprising: a reading circuit coupled to said fingerbiometric sensing layer for reading signals therefrom; and a power upcircuit for selectively powering up said reading circuit based upon saidsense circuit.
 5. The finger biometric sensor according to claim 3wherein said sense circuit generates a pressure output signal related toan amount of pressure applied by the user's finger.
 6. The fingerbiometric sensor according to claim 1 further comprising a matchercoupled to said finger biometric sensing layer for determining a matchbased upon the at least one biometric characteristic of the user'sfinger.
 7. The finger biometric sensor according to claim 1 furthercomprising a navigation circuit coupled to said transducer electrodesfor performing at least one navigation function.
 8. The finger biometricsensor according to claim 1 further comprising a feedback circuitcoupled to said transducer electrodes for performing at least onefeedback function.
 9. The finger biometric sensor according to claim 1wherein said finger biometric sensing layer comprises an integratedcircuit.
 10. The finger biometric sensor according to claim 1 furthercomprising a mounting substrate below said piezoelectric transducerlayer.
 11. A finger biometric sensor comprising: a finger biometricsensing layer having opposing first and second major surfaces and forgenerating signals related to at least one biometric characteristic of auser's finger when positioned adjacent the first major surface; apiezoelectric transducer layer coupled to the second major surface ofsaid finger biometric sensing layer; and a plurality of electricallyconductive layers coupled to said piezoelectric transducer layer todefine transducer electrodes; a finger drive electrode adjacent saidfinger biometric sensing layer and said piezoelectric transducer layer,and configured to couple a radio frequency (RF) signal with the user'sfinger; a drive circuit coupled to said first and second transducerelectrodes to drive said piezoelectric transducer layer to impart aforce to the user's finger; and a sense circuit coupled to said firstand second transducer electrodes to sense from said piezoelectrictransducer layer a force imparted by the user's finger.
 12. The fingerbiometric sensor according to claim 11 further comprising: a readingcircuit coupled to said finger biometric sensing layer for readingsignals therefrom; and a power up circuit for selectively powering upsaid reading circuit based upon said sense circuit.
 13. The fingerbiometric sensor according to claim 11 wherein said sense circuitgenerates a pressure output signal related to an amount of pressureapplied by the user's finger.
 14. The finger biometric sensor accordingto claim 11 further comprising a matcher coupled to said fingerbiometric sensing layer for determining a match based upon the at leastone biometric characteristic of the user's finger.
 15. The fingerbiometric sensor according to claim 11 further comprising a navigationcircuit coupled to said transducer electrodes for performing at leastone navigation function.
 16. The finger biometric sensor according toclaim 11 further comprising a feedback circuit coupled to saidtransducer electrodes for performing at least one feedback function. 17.A method of making a finger biometric sensor comprising: providing afinger biometric sensing layer having opposing first and second majorsurfaces and for generating signals related to at least one biometriccharacteristic of a user's finger when positioned adjacent the firstmajor surface; coupling a piezoelectric transducer layer to the secondmajor surface of the finger biometric sensing layer; coupling aplurality of electrically conductive layers to the piezoelectrictransducer layer to define transducer electrodes; and positioning afinger drive electrode adjacent the finger biometric sensing layer andthe piezoelectric transducer layer, the finger drive electrode forcoupling a radio frequency (RF) signal with the user's finger.
 18. Themethod according to claim 17 further comprising coupling a drive circuitcoupled to the transducer electrodes to drive the piezoelectrictransducer layer to impart a force to the user's finger.
 19. The methodaccording to claim 17 further comprising coupling a sense circuit to thetransducer electrodes to sense from the piezoelectric transducer layer aforce imparted by the user's finger.
 20. The method according to claim17 further comprising: coupling a reading circuit to the fingerbiometric sensing layer for reading signals therefrom; and providing apower up circuit for selectively powering up the reading circuit basedupon the sense circuit.
 21. The method according to claim 19 wherein thesense circuit generates a pressure output signal related to an amount ofpressure applied by the user's finger.
 22. The method according to claim17 further comprising coupling a matcher to the finger biometric sensinglayer for determining a match based upon the at least one biometriccharacteristic of the user's finger.
 23. A finger biometric sensorcomprising: a finger biometric sensing layer having opposing first andsecond major surfaces and comprising a plurality of electric fieldsensing pixels for generating signals related to at least one biometriccharacteristic of a user's finger when positioned adjacent the firstmajor surface, the generated signals based upon a respective sensedelectric field; a piezoelectric transducer layer adjacent the secondmajor surface of said finger biometric sensing layer; and a plurality ofelectrically conductive layers coupled to said piezoelectric transducerlayer to define transducer electrodes.
 24. The finger biometric sensoraccording to claim 23 further comprising a drive circuit coupled to saidtransducer electrodes to drive said piezoelectric transducer layer toimpart a force to the user's finger.
 25. The finger biometric sensoraccording to claim 23 further comprising a sense circuit coupled to saidtransducer electrodes to sense from said piezoelectric transducer layera force imparted by the user's finger.
 26. The finger biometric sensoraccording to claim 25 further comprising: a reading circuit coupled tosaid finger biometric sensing layer for reading signals therefrom; and apower up circuit for selectively powering up said reading circuit basedupon said sense circuit.
 27. The finger biometric sensor according toclaim 25 wherein said sense circuit generates a pressure output signalrelated to an amount of pressure applied by the user's finger.
 28. Thefinger biometric sensor according to claim 23 further comprising amatcher coupled to said finger biometric sensing layer for determining amatch based upon the at least one biometric characteristic of the user'sfinger.
 29. The finger biometric sensor according to claim 23 furthercomprising a navigation circuit coupled to said transducer electrodesfor performing at least one navigation function.
 30. The fingerbiometric sensor according to claim 23 further comprising a feedbackcircuit coupled to said transducer electrodes for performing at leastone feedback function.